Electromagnetic device



P. B. MURPHY ELECTROMAGNETIC DEVICE Original Filed July 14, 1927 FIG. 4.

INVENTOP P. B. MURPHY A TORNEY Patented Mar. 24, 1936 ELECTROMAGNETIC DEVICE Paul B. Murphy, Nyack, N. Y., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Original application July 14, 1927, Serial No. 205,542. Divided and this application August 25, 1934, Serial No. 741,373

5 Claims.

This invention relates to a combined magnetic and thermostatic relay and particularly to a relay of this type for closing and opening circuits periodically.

This application is a division of the applicants copending application, Serial No. 205,542, filed July 14, 1927.

The invention provides means for interrupting a circuit at certain intervals a predetermined period after the original closing thereof. This means may comprise a magnetic relay provided with a thermostatic element usually in the form of an armature spring having a heater winding. This spring is controlled by the operation of the relay. When said relay is energized a circuit connection is established through the heater winding, thus causing the spring to be heated and bent to open the circuit through its winding. When the spring cools off the circuit is reestablished and thereafter this circuit is interrupted at a uniform rate until the relay is deenergized.

The arrangement of the armature spring may be such that the period of time it takes to heat the spring to originally open its circuit is different from the succeeding open and closed periods of the circuit. It is evident that the spring may during its operation control independent electrical circuits in the same manner. For example, it may close or open a circuit a predetermined period beginning at the energization of the relay and thereafter interrupting this circuit at a uniform rate; the periods of the interruptions and the periods of the closure of the circuit may be of shorter duration than the original closed or open period.

The invention has been illustrated in the accompanying drawing in which Fig. 1 shows a relay in diagrammatic form with a thermostatic element and circuits arranged in accordance with this invention. Fig. 2 shows a relay with the thermostatic element controlled by a separate armature. Figs. 3 and 4 show the relay adapted for use in telephone systems to flash signals.

Referring now to the drawing, in Fig. 1 the invention has been carried out by means of a relay l having an armature in the form of a thermostatic element 2, on which a heater winding 3 has been placed. The arrangement is such that when the relay attracts armature 2 this armature will be moved towards the left until it comes in contact with the insulating stop 4 and closes a circuit through contact 5. This circuit now extends from battery through the armature 2, contact 5, heater winding 3 to ground. The current through the winding 3 heats the armature 2 and due to the thermostatic character of this armature, it will bend towards the right after having been heated sufficiently to open the connection between itself and the contact 5. t will, as is well known in the art, maintain the circuit open until it cools off sufficiently to again close the circuit. When this takes place the armature 2 is again heated to again open the circuit. This movement of the armature 2 alternately towards the right and towards the left will now continue as long as the relay is operated. The movement of the armature 2 may be utilized, for example to open and close a circuit from battery through the armature 2 and contact 5 to conductor 6 for opening and closing connections through this conductor.

The thermostatic element 2 of Fig. 1 may be of any well-known construction. As shown in the drawing it comprises two strips of metal.

These strips have different temperature coeiiicients, and together form a bimetal switch or circuit closing element which bends or warps when heated by the surrounding winding 3.

Referring now to Fig. 2, the invention may be applied in a somewhat different manner. lay i may be provided with an armature l and a thermostatic device in the form of a spring 8 so arranged that when the relay attracts the armature I the spring 8 will follow the movement of the armature due to the fact that it has a slight tension towards the left. When this spring comes in contact with a spring 9 the tensionof the spring 8 may be such as to overcome the tension of spring 9 to move this latter spring until it comes in contact with the stop I 0. from battery, spring 8, contact 9, heater winding H to ground. The current through winding H heats the spring 8 and, due to its thermostatic character, this spring will bend towards the right. After having been heated sufficiently to open the connection between itself and the spring 9, it will maintain the circuit open until it cools off sufliciently to again close the circuit. When this takes place the spring 8 is again heated to again open the circuit. This movement of the spring 8 alternately towards the right and towards the left now continues as long as the relay is operated. The movement of spring 8 may be utilized for example, to open and close circuits through a spring l2, attached to spring 8, and contacts I3 and Hi.

It should be observed that the adjustment of the springs 8 and 9 and stop Ill may be such that the period of time elapsed between the original closing and opening of the connection be- The re- A circuit is now closed tween spring I2 and contact l4, and the original opening and closing of the connection between spring I2 and contact [3 is longer than the succeeding closing and opening periods between the spring l 2 and these contacts. For example, when the spring 8 is originally moved towards the left the period of connection between spring l2 and contact I 4 begins; then when spring 8 is gradually heated spring 9 will maintain the circuit closed for a certain period as long as it will follow spring 8 as it continues to bend towards the right. This period may be made longer as compared with the period it takes the spring 8 to cool sufficiently to again close this circuit and the period it takes to reheat it to open this circuit thereafter.

The circuit connections between the spring I2 and contacts l3 and M or circuit connections established, as for example, by the armature 2 itself, may be used in telephone systems for various circuit closing and opening purposes. For example, in Figs. 3 and 4 means is shown for operating a line signal and flashing it at a predetermined period of time after the original operation thereof. In Fig. 3 the line relay I 6 in operating permits the thermostatic armature I! to close a circuit for a heater Winding l8 from battery, armature and back contact of sleeve relay l9, spring i1, contact 20, heater winding I8 to ground. A circuit is also closed from this battery at relay l9 toground to the line signal 2|. Lamp 2| is lighted and if an operator answers the call by inserting the usual plug into jack 22, relay !9 will be operated. This relay when operating opens the circuits for the heater winding l8 and lamp 2! to permit the spring I! to cool and lamp 2| to be extinguished.

On the other hand, if the operator does not answer the call within the period of time it takes to heat the spring I! to open the connection through contact 20, the circuit for lamp 2| will be opened and closed thereafter at fixed intervals in the manner explained in connection with contact 5 in Fig. 1, or contacts l3 and I4 and spring I in Fig. 2. Thus lamp 2! will be alternately extinguished and lighted until the operator answers the call when the circuit for lamp 2| will be broken as hereinbefore described.

In Fig. 4 the actions are practically the same as in Fig, 3 except that the line relay 23 closes an obvious circuit for relay 24 which acts in the same manner as relay H5 in Fig. 3 and the sleeve relay 25 opens the circuit to release relay 24 instead of opening the lamp circuit directly as in Fi 3.

While this invention has been illustrated merely in two different forms it should be understood that it is applicable in many other forms without departing from the spirit thereof.

What is claimed is:

1. In a telephone system, a line, a relay bridged across the conductors of said line, a thermostatic armature, a heating winding, a signal, a normally open circuit including said heating winding, said armature and said signal, said elements being so arranged that when the armature is attracted by the operation of the relay the circuit is alternately closed and opened due to the thermostatic action of the armature.

2. In a telephone system, a line, a relay bridged across the conductor of said line, a thermostatic armature, a heating winding, a signal, a normally open circuit including said heating winding, said armature and said signal, said elements being so arranged that when the armature is attracted by the energization of the relay the circuit is closed a predetermined period of time and thereafter opened and closed for fixed and equal periods of a shorter duration than the first mentioned predetermined period of time.

3. A telephone system including a line lamp, a line relay for lighting said line lamp, and a bimetal warp switch arranged to flash said line lamp alternately oh and on after being initially lighted.

4. A telephone system including a line lamp, a line relay for lighting said line lamp, and a bimetal warp switch arranged to alternately flash said line lamp on and off after said line relay has been operated for a predetermined length of time.

5. In a telephone system, a line relay, a line lamp, a bimetal warp, a circuit to ground for said lamp, a circuit to ground for said warp, a source of current, and means for closing said circuits to said source under control of said relay and for thereafter opening and closing said circuits at regular intervals under control of said bimetal warp.

PAUL B. MURPHY. 

